Let me know wich faction/scenario you want to make playable and I will do a kind a Template step by step that could be reuse for others factions/scenarios.

2 points ;

The main difference between non playable and playable factions is hundreds of hours of work. So there is a risk that factions that are designed not to be playable would be quite boring to play.These ''mods'' will never been official.

Removing the SetFacUnselect command in the excel file allows me to at least look at other factions as long as there are not more than three other factions in play (more than this and I think there will be an error).

Run the game. As soon as you see the message about loading textures (10%...), strike on the F9 key.
You will noticed on the top right-hand side of the loading screen the mention “Editor Mode”.
Wait until you see the game map and your scenario units magically appears in front of you…
If they don’t, you’ll either get an error message or nothing (more exactly you get the load menu)…in which case you did something wrong in the previous steps!
7 ; – Check and Save

Once the scenario appears on the screen, you can have a look around it as you wish.
Then click on the save button.
Your scenario is now saved.

The new scn file should overwrite the existing MS87 one (1-MariusSulla87.scn in AJE/scens). You can do a backup of it before going through the step by step process for safety purpose.